Electrospinning head and electrospinning apparatus

ABSTRACT

According to one embodiment, an electrospinning head includes a head main body and a nozzle. The nozzle projects from the head main body. A flow passage is formed inside the nozzle, and an ejection port of the flow passage is formed at a projecting end of the nozzle. A first extending portion constitutes a connecting portion of the nozzle to the head main body, and a second extending portion further projects from the first extending portion and constitutes the projecting end of the nozzle. A volume in the second extending portion excluding the flow passage is smaller than that in the first extending portion, and a dimension of the second extending portion along a projection direction is smaller than that of the first extending portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2019-162011, filed Sep. 5, 2019, the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate to an electrospinning head and an electrospinning apparatus.

BACKGROUND

An electrospinning apparatus that accumulates microfibers on a collection body or the surface of a substrate to form a fiber film with an electrospinning method (sometimes called “electric charge induction spinning method”). In such an electrospinning apparatus, an electrospinning head is provided, and the electrospinning head includes a head main body and a nozzle projecting from the outer peripheral surface of the head main body. In the electrospinning head, a storage hollow for storing a material liquid is formed in the inside of the head main body. In the inside of the nozzle, a flow passage (nozzle flow passage) communicating with the storage hollow is formed, and an ejection port of the flow passage is formed at the projecting end of the nozzle from the head main body. A voltage is applied between the nozzles (electrospinning head) and a collection body or a substrate so as to eject a material liquid against the surface of the collection body or the substrate, thereby accumulating fiber thereon.

With the above-described electrospinning apparatus, in the flow passage of each nozzle, there is a demand to secure a high charge density of a material liquid immediately before being ejected from the ejection port and to eject the material liquid appropriately against the collection body and the substrate from the ejection port. Furthermore, there is a demand to prevent an excessive electric field in the space in the vicinity of the projecting end of the nozzle, and to effectively prevent adhesion of fiber to the projecting end of the nozzle and the vicinity thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing an example of an electrospinning apparatus according to a first embodiment.

FIG. 2 is a schematic diagram showing an electrospinning head according to the first embodiment.

FIG. 3 is a cross-sectional view schematically showing the electrospinning head according to the first embodiment in a cross section perpendicular or substantially perpendicular to a longitudinal direction and passing one nozzle.

FIG. 4 is a cross-sectional view schematically showing the electrospinning head according to a first modification in a cross section perpendicular or substantially perpendicular to a longitudinal direction and passing one nozzle.

FIG. 5 is a cross-sectional view schematically showing the electrospinning head according to a second modification in a cross section perpendicular or substantially perpendicular to a longitudinal direction and passing one nozzle.

FIG. 6 is a schematic diagram showing an electrospinning head according to a third modification.

DETAILED DESCRIPTION

According to one embodiment, an electrospinning head including a head main body and a nozzle is provided. Inside the head main body, a storage hollow capable of storing a material liquid is formed. The nozzle is made of an electrically conductive material, and projects from the outer peripheral surface of the head main body. In the nozzle, a flow passage communicating with the storage hollow is formed in the inside, and an ejection port of the flow passage is formed at a projecting end of the nozzle from the head main body. The nozzle includes a first extending portion and a second extending portion. The first extending portion constitutes a connecting portion of the nozzle connecting to the outer peripheral surface of the head main body, and the part of the first extending portion excluding the flow passage makes up a first volume. The second extending portion further projects from the first extending portion toward the projection direction of the nozzle, and constitutes the projecting end of the nozzle. The part of the second extending portion excluding the flow passage makes up a second volume smaller than the first volume, and a dimension of the second extending portion along the projection direction is smaller than that of the first extending portion.

According to an embodiment, an electrospinning apparatus including the above-described electrospinning head and an electric power source is provided. The electric power source applies a voltage to the nozzle of the electrospinning head.

Hereinafter, the embodiments will be described with reference to the accompanying drawings.

First Embodiment

FIG. 1 shows an example of an electrospinning apparatus according to the first embodiment. As shown in FIG. 1, the electrospinning apparatus 1 has an electrospinning head 2, a supply source (supplier) 3 of a material liquid, an electric power source 4, a collection body 5, and a controller 6.

FIGS. 2 and 3 show a configuration of the electrospinning head 2. As shown in FIGS. 1 through 3, the electrospinning head 2 has a head main body 11 and a plurality of (four in the present embodiment) nozzles 12. The head main body 11 (electrospinning head 2) has a longitudinal axis C as a center axis, and extends along the longitudinal axis C. In the present embodiment, each of the head main body 11 and the nozzles 12 is made of an electrically conductive material.

The number of the nozzles 12 is not limited particularly, and at least one nozzle will suffice. Preferably, the head main body 11 and each of the nozzles 12 are respectively made of materials having resistance against a material liquid, which will be described later, and may be made of stainless steel, for example. Herein, FIG. 2 shows the electrospinning head 2 viewed in a direction intersecting with (perpendicular or substantially perpendicular to) the longitudinal axis C. FIG. 3 shows a cross section perpendicular or substantially perpendicular to the longitudinal axis C and passing one of the nozzles 12.

Each of the nozzles 12 is provided on the outer peripheral surface of the head main body 11. The outer peripheral surface of the head main body 11 extends around the longitudinal axis C, and constitutes a part of the outer surface of the head main body 11. Furthermore, the outer peripheral surface of the head main body 11 faces a side away from the longitudinal axis C in the direction intersecting with (perpendicular or substantially perpendicular to) the longitudinal axis C. In the present embodiment, the plurality of nozzles 12 are arranged at the same or substantially the same angle positions in a direction around the longitudinal axis C. For this reason, in the present embodiment, the plurality of nozzles 12 are arranged along the longitudinal axis C, and constitute the nozzle row 13. Each of the nozzles 12 projects from the outer peripheral surface of the head main body 11 toward the outer periphery side, in other words, toward the side away from the longitudinal axis C.

In the inside of the head main body 11, a storage hollow 15 is formed along the longitudinal axis C. In the present embodiment, the storage hollow 15 is formed coaxially or substantially coaxially with the head main body 11, and the center axis of the storage hollow 15 is formed coaxially or substantially coaxially with the longitudinal axis C. The storage hollow 15 is formed over an entirety of or most of the head main body 11 in the direction along the longitudinal axis C. For this reason, in the present embodiment, the head main body 11 is formed in a cylindrical shape having the storage hollow 15 as an internal hollow.

In the electrospinning head 2, the flow passages (nozzle flow passages) 17 of the same number as that of the nozzles 12 are formed, and one flow passage 17 is formed in the inside of each nozzle 12. One end of each flow passage 17 communicates with the storage hollow 15, and each flow passage 17 extends from the storage hollow 15 toward the outer periphery side of the head main body 11. In each flow passage 17, an ejection port 18 is formed at the other end opposite to the storage hollow 15, and each flow passage 17 opens outwardly at the ejection port 18. The ejection port 18 of each flow passage 17 is arranged at the projecting end E2 of the corresponding one nozzle 12 from the outer peripheral surface of the head main body 11.

The supply source 3 of a material liquid includes a storage 31, a supply driver 32, a supply adjuster 33, and a supply pipe 35. Each of the storage 31, the supply driver 32, the supply adjuster 33, and the supply pipe 35 has resistance to a material liquid, and in one example, each of the storage 31 and the supply pipe 35 is made of an insulating material, such as a fluorine resin.

The storage 31 is a reservoir, etc. for storing material liquids. A material liquid is a solution of a high-polymer material in a solvent. The high polymer included in the material liquid, and the solvent in which the high polymer is dissolved are determined as appropriate in accordance with the type, etc. of fiber 100 to be accumulated on the surface of the collection body 5. The supply pipe 35 connects the storage 31 to the head main body 11 of the electrospinning head 2. In the inside of the supply pipe 35, a flow passage for a material liquid is formed.

An opening 16 is formed at one of the ends of the storage hollow 15 of the head main body 11. The supply pipe 35 is connected to the head main body 11 at the opening 16, and the storage hollow 15 communicates with the inside of the supply pipe 35 at the opening 16. In the present embodiment, the opening 16 is formed on one of the end surfaces of the head main body 11 in the direction along the longitudinal axis C. The other end of the storage hollow 15, namely the end opposite to the opening 16 of the storage hollow 15, is closed relative to the outside of the head main body 11. In one example, the other end of the storage hollow 15 is closed by the head main body 11 itself; in another example, the other end of the storage hollow 15 is closed by a lid member, etc. attached to the head main body 11.

The supply driver 32 is operated to supply a material liquid to the storage hollow 15 of the head main body 11 from the storage 31 through the supply pipe 35. In one example, the supply driver 32 is a pump. In another example, the supply driver 32 supplies a gas to the storage 31 to transmit the liquid material under pressure from the storage 31 to the storage hollow 15. The storage hollow 15 is capable of storing the material liquid supplied through the supply pipe 35.

The supply adjuster 33 adjusts an amount of flow and a pressure, etc. of the material liquid supplied to the storage hollow 15. In one example, the supply adjuster 33 is a controlling valve capable of controlling an amount of flow and a pressure, etc. of a material liquid. The supply adjuster 33 adjusts the amount of flow and the pressure of the material liquid to suppress the ejection of the material liquid from the ejection port 18 of each nozzle 12 in a state where no voltage is applied between the electrospinning head 2 and the collection body 5. Furthermore, the supply adjuster 33 adjusts the amount of flow and the pressure, etc. of the material liquid as appropriate based on a viscosity of the material liquid, the dimensions of the ejection port 18, and the like. In one example, the supply adjuster 33 is capable of switching between supply and no supply of the material liquid from the storage 31 to the storage hollow 15. In this case, the supply adjuster 33 is for example a switching valve.

It is not always necessary to provide the supply driver 32 and the supply adjuster 33. In one example, the storage 31 is provided vertically above the head main body 11, and the material liquid is supplied by gravity from the storage 31 to the storage hollow 15. In this case, through adjusting a difference in height between the head main body 11 and the storage 31, the ejection of the material liquid from the ejection port 18 of each nozzle 12 is suppressed in a state where no voltage is applied between the electrospinning head 2 and the collection body 5.

The electric power source 4 applies a voltage between the electrospinning head 2 and the collection body 5. At this time, in the electrospinning head 2, a voltage of a predetermined polarity is applied to each nozzle 12 through the head main body 11. In one example, a terminal (not shown) electrically connected to each nozzle 12 is provided, and a voltage is applied to each nozzle 12 through the terminal. In the configuration in which the terminals are provided, there is no need to make the head main body 11 from an electrically conductive material. As described above, any configuration can be adopted as the electric power source 4 as long as it applies a voltage to each nozzle 12.

The nozzles 12 are electrically connected to each other. For this reason, in a state where a voltage is applied to each nozzle 12, the nozzles 12 are at the same or substantially the same electric potential. The polarity of the voltage applied to each nozzle 12 may be positive or negative. In the example shown in FIG. 1, the electric power source 4 is a direct current power source, and applies a positive voltage to each nozzle 12.

The collection body 5 is made of an electrically conductive material. The collection body 5 has resistance against the material liquid, and in one example, it is made of stainless steel. The collection body 5 is arranged at the side on which each ejection port 18 opens with respect to the electrospinning head 2. Accordingly, with respect to the electrospinning head 2, the collection body 5 is arranged on the side where the material liquid is ejected from each ejection port 18.

In the example shown in FIG. 1, the collection body 5 is grounded. For this reason, in the state where a positive voltage is applied to each nozzle 12, the voltage of the collection body 5 relative to the ground becomes 0 V or substantially 0 V. In another example, the collection body 5 is not grounded. The electric power source 4 applies to the collection body 5 a voltage of opposite polarity to that applied to each nozzle 12.

In the state where the electrospinning head 2 is supplied with the material liquid by the supply source, the material liquid is ejected against the collection body 5 from the ejection port 18 of each nozzle 12 by applying a voltage between each nozzle 12 and the collection body 5 by the electric power source 4 in the above-described manner. In other words, the electric potential difference between each nozzle 12 and the collection body 5 causes the ejection of the material liquid against the collection body 5. Through the ejection of the material liquid against the collection body 5 from the ejection port 18 of each nozzle 12, the fiber 100 is accumulated on the surface of the collection body 5, and the accumulated fiber 100 forms a film of the fiber 100. In other words, the film of the fiber 100 is formed by the electrospinning method (sometimes referred to as “electric charge induction spinning method”).

The voltage applied between the electrospinning head 2 and the collection body 5, namely the electric potential difference between each nozzle 12 and the collection body 5, is adjusted to be of an appropriate value in accordance with the type of the high polymer included in the material liquid and a distance between each nozzle 2 and the collection body 5, and the like. In one example, a direct current voltage in the range of 10 kV to 100 kV is applied between each nozzle 12 and the collection body 5.

The collection body 5 is formed in a plate-like shape or a sheet-like shape, for example. In the case where the collection body 5 is formed in a sheet-like shape, the fiber 100 may be accumulated on the collection body 5 rolled around the outer peripheral surface of a roll or the like. The collection body 5 may be movable.

In one example, a pair of rotating drums, and a drive source that drives the drums are provided. Through the driving of the rotating drums by the drive source, the collection body 5 is moved between the pair of rotating drums, in a manner similar to a belt conveyor. Through the moving (transfer) of the collection body 5, it is possible to change the area where the fiber 100 is accumulated on the surface of the collection body 5 over time. It is thus possible to continuously accumulate the fiber 100 on the collection body 5 over time, thereby effectively producing a film of the fiber 100, which is an accumulation of the fiber 100.

The film of the fiber 100 formed on the surface of the collection body 5 is removed from the collection body 5. The film of the fiber 100 is used as a nonwoven fabric or a filter, etc., but the usage is not limited thereto.

In one example, the collection body 5 is not provided. In this case, a substrate made of an electrically conductive material is used, and a voltage is applied between the substrate and each nozzle 12, thereby ejecting the material liquid toward the substrate from the ejection port 18 of each nozzle 21. Then, through the accumulation of the fiber 100 on the surface of the substrate, the film of the fiber 100 is formed on the surface of the substrate. In this case, the substrate may be grounded, and a voltage of an opposite polarity to the voltage applied to each nozzle 12 may be applied to the substrate by the electric power source 4.

In another example, the substrate is arranged on the collection body 5, and a voltage is applied between each nozzle 12 and the collection body 5 as described above. Then, the fiber 100 is accumulated on the surface of the substrate arranged on the collection body 5, and a film of the fiber 100 is formed on the surface of the substrate. In this case, even if the substrate has electrically insulating properties, it is possible to form a film of the fiber 100 on the surface of the substrate.

In the case where the substrate is arranged on the collection body 5, the substrate may be movable on the collection body 5. In one example, a rotating drum around which the substrate in a sheet-like shape is rolled, and a rotating drum that winds around itself the substrate on which the film of the fiber 100 is formed thereon are provided. Furthermore, the substrate is moved on the collection body 5 as a result of the rotation of each rotating drum. Through the moving (transfer) of the substrate, it is possible to change the area where the fiber 100 is accumulated on the surface of the substrate over time. It is thus possible to continuously accumulate the fiber 100 on the substrate over time, thereby effectively producing a film of the fiber 100, which is an accumulation of the fiber 100.

As an example where the film of the fiber 100 is formed on the surface of the substrate, although not limited thereto, manufacturing of a separator-integrated type electrode for a battery is known. In this case, either one of the negative electrode or the positive electrode of an electrode group may be used as the substrate. The film of the fiber 100 formed on the surface of the substrate serves as a separator integrated with the negative electrode or the positive electrode.

The controller 6 is a computer, for example. The controller 6 includes a processor or an integrated circuit (control circuit) including a CPU (central processing unit), an ASIC (application specific integrated circuit), or an FPGA (field programmable gate array), and a storage medium, such as a memory. The controller 6 may include only one integrated circuit, etc., or a plurality of integrated circuits, etc. The controller 6 performs processing by executing a program, etc. stored on the storage medium, etc. The controller 6 controls the driving of the supply driver 32, the operation of the supply adjuster 33, and the output from the electric power source 4, etc.

Each nozzle 12 is a needle-type nozzle, for example, and has an extension axis P as a center axis. In each nozzle 12, one of the directions (indicated by arrows X1 and X2) along the extension axis P matches or substantially matches the direction of the projection of the nozzle 12 from the outer peripheral surface of the head main body 11. Each flow passage (nozzle flow passage) 17 is formed coaxially or substantially coaxially with respect to a corresponding one of the nozzles 12, and the center axis of each flow passage 17 is formed coaxially or substantially coaxially with respect to the extension axis P of a corresponding one of the nozzles 12. Each flow passage 17 is formed along the corresponding extension axis P of the nozzle 12. Furthermore, the flow passage 17 in a corresponding nozzle 12 is formed over the entire length in the direction along the extension axis P. For this reason, in the present embodiment, each nozzle 12 is formed in a cylindrical shape having the corresponding flow passage 17 as an internal hollow.

Each nozzle 12 includes extending portions (extensions) 21 and 22. In each nozzle 12, the connecting portion E1 connected to the outer peripheral surface of the head main body 11 is constituted by the extending portion (first extending portion) 21. Accordingly, in each nozzle 12, the root of the projection from the head main body 11 is constituted by the extending portion 21. In each nozzle 12, the extending portion (second extending portion) 22 further projects from the extending portion 21 toward the projection direction (the direction indicated by arrow X1), and the extending portion 22 constitutes the projecting end E2 of the projecting portion from the head main body 11. Accordingly, in each nozzle 12, one ejection port 18 is formed at the projecting end (distal end) of the extending portion 22.

In each nozzle 12, a connecting portion E3 connecting the extending portions 21 and 22 is formed. In each nozzle 12, the extending portion (second extending portion) 22 is connected, at the connecting portion E3, to the extending portion (first extending portion) 21 on the side where the projecting end E2 is located. In each nozzle 12, a flow passage 17 extends from the storage hollow 15 to the ejection port 18 (projecting end E2), through the inside of the extending portion 21 and then the inside of the extending portion 22. With the above-described configuration, in each nozzle 12, the extending portion 22 constitutes a nozzle distal portion where the projecting end E2 is formed, and the extending portion 21 constitutes a nozzle relaying portion that relays the head main body 11 to the extending portion 22.

In each nozzle 12, the area of the cross sectional area of the flow passage 17 perpendicular to the extension axis P becomes uniform from the connecting portion E1 to the head main body 11 to the projecting end E2. In other words, the cross sectional area of each flow passage 17 perpendicular to the direction in which the flow passage 17 extends becomes constant or substantially constant from the connecting portion E1 to the head main body 11 to the projecting end E2 in a corresponding one of the nozzles 12. Accordingly, in each nozzle 12, between the connecting portion E1 and the projecting end E2, the area of the cross section of the flow passage 17 perpendicular to the direction in which the flow passage 17 extends does not fluctuate, or minutely fluctuate only to the extent that the fluctuation is assumed to be ignorable. In one example, the outer diameter of the nozzle 12 at the projecting end E2 is designed to be 0.5 mm, and the diameter (inner diameter) of the flow passage 17 is designed to be 0.3 mm. In this case, as long as the diameter of the flow passage 17 falls within the range of 0.3 mm±a few microns between the connecting portion E1 and the projecting end E2, the cross-sectional area of the flow passage 17 is assumed to be uniform (constant or substantially constant) from the connecting portion E1 to the projecting end E2.

In each of the nozzles 12 according to the present embodiment, the outer diameter of the extending portion (second extending portion) 22 is smaller than the outer diameter of the extending portion (first extending portion) 21. In other words, the distance from the extension axis P to the outer peripheral surface of the extending portion 22 is smaller than the distance from the extension axis P to the outer peripheral surface of the extending portion 21. In each nozzle 12, the outer diameter of the extending portion 22 becomes uniform (constant or substantially constant) from the connecting portion E1 connecting to the head main body 11 to the connecting portion E3 (the projecting end of the extending portion 21) connecting to the extending portion 22. In each nozzle 12, the outer diameter of the extending portion 22 becomes uniform (constant or substantially constant) from the connecting portion E3 connected to the extending portion 21 (the root of the extending portion 22) to the projecting end E2. In one example, the outer diameter of the extending portion 22, namely the outer diameter of the projecting end E2 of the nozzle 12, is designed to be 0.5 mm. In this case, as long as the outer diameter of the extending portion 22 falls within the range of 0.5 mm±a few microns between the connecting portion E3 and the projecting end E2, the outer diameter of the extending portion 22 is assumed to be uniform from the connecting portion E3 to the projecting end E2, and the distance from the extension axis P to the outer peripheral surface of the extending portion 22 is assumed to be uniform between the connecting portion E3 and the projecting end E2.

In each nozzle 12, the outer diameter of the extending portion (second extending portion) 22, namely the outer diameter at the projecting end E2, is preferably as small as possible. If the outer diameter of the extending portion 22 is reduced in each nozzle 12, a concentration of an electrical field tends to occur in the proximity of the projecting end E2 (ejection port 18) of each nozzle 12. In one example, the outer diameter of the extending portion 22 of each nozzle 12 falls within the range of 0.3 mm to 1.3 mm, for example.

The diameter (inner diameter) of each flow passage 17, in other words, the opening diameter of each ejection port 18 is not limited to a particular value, as long as the diameter is smaller than the outer diameter of the extending portion 22 of the corresponding nozzle 12. The diameter of each flow passage 17 is set as appropriate in accordance with a type, etc. of the fiber 100 to be accumulated on the surface of the collection body 5. In one example, the diameter of each flow passage 17 falls within the range of 0.1 mm to 1 mm, for example.

Since the outer diameters of the extending portions 21 and 22 are formed in the above-described manner, the outer diameter of the nozzle 12 decreases, from the extending portion 21 toward the extending portion 22, in the connecting portion E3 between the extending portions 21 and 22. For this reason, in each nozzle 12, a step in a radial direction is formed in the connecting portion E3 connecting the extending portions 21 and 22. Since the outer diameters of the extending portions 21 and 22 and the diameter of the flow passage 17 are formed in the above-described manner, in each nozzle 12, the thickness of the extending portion 22 from the flow passage 17 to the outer peripheral surface is smaller than the thickness of the extending portion 21 from the flow passage 17 to the outer peripheral surface. In other words, the thickness of the extending portion (second extension) 22 from the flow passage 17 to the outer peripheral surface is smaller than the thickness of the extending portion (first extension) 21 from the flow passage 17 to the outer peripheral surface.

In the extending portion 21 of each nozzle 12, the thickness from the flow passage 17 to the outer peripheral surface becomes uniform (constant or substantially constant) from the connecting portion E1 connecting to the head main body 11 to the connecting portion E3 (the projecting end of the extending portion 21) connecting to the extending portion 22. Thus, if the thickness of the connecting portion (position of connection) E1 connecting to the head main body 11 from the flow passage 17 to the outer peripheral surface is defined as “thickness T1”, the thickness of any site between the connecting portion E1 and the connecting portion E3 from the flow passage 17 to the outer peripheral surface is the same or substantially the same as the thickness T1 in the extending portion 21 of each nozzle 12. In the extending portion 22 of each nozzle 12, the thickness from the flow passage 17 to the outer peripheral surface becomes uniform (constant or substantially constant) from the connecting portion E3 connecting to the extending portion 21 (the root of the extending portion 22) to the projecting end E2. Thus, if the thickness of the projecting end E2 from the flow passage 17 to the outer peripheral surface is defined as “thickness T2”, the thickness of any site between the connecting portion E3 and the projecting end E2 from the flow passage 17 to the outer peripheral surface is the same or substantially the same as the thickness T2 in the extending portion 22 of each nozzle 12. In one example, the thickness T2 of the extending portion 22, namely the thickness of the projecting end E2 of the nozzle 12 from the flow passage 17 to the outer peripheral surface, is designed to be 0.2 mm. In this case, as long as the thickness of the extending portion 22 falls within the range of 0.2 mm±a few microns from the connecting portion E3 to the projecting end E2, the thickness of the extending portion 22 is assumed to be uniform from the connecting portion E3 to the projecting end E2.

In the present embodiment, as described above, the thickness of the extending portion 22 is smaller than that of the extending portion 21. Accordingly, the cross-sectional area of the extending portion 22 excluding the flow passage 17 in the cross section perpendicular to the extension axis P is smaller than the cross-sectional area of the extending portion 21 excluding the flow passage 17 in the cross section perpendicular to the extension axis P. In other words, in each nozzle 12, the volume per unit length in the direction (projection direction) along the extension P is smaller in the part of the extending portion (second extending portion) 22 excluding the flow passage than in the part of the extending portion (first extending portion) 21 excluding the flow passage.

In each nozzle 12, the dimension L2 of the extending portion 22 in the direction along the extension axis P is smaller than the dimension L1 of the extending portion 21 in the direction along the extension axis P. In other words, in each nozzle 12, the dimension L2 of the extending portion 22 along the projection direction is smaller than the dimension L1 of the extending portion 21 along the projection direction. Furthermore, in each nozzle 12, the extension length of the flow passage 17 from the connecting portion E1 connecting to the head main body 11 to the projecting end E2 is the same or approximately the same as a sum of the dimensions L1 and L2 (i.e., L1+L2).

Herein, the volume of the extending portion (first extending portion) 21 excluding the flow passage 17 is defined as V1, and the volume of the extending portion (second extending portion) 22 excluding the flow passage 17 is defined as V2. In the present embodiment, the cross-sectional area and the dimension L1 of the extending portion 21 are as described above, and the cross-sectional area and the dimension L2 of the extending portion 22 are as described above. For this reason, in each nozzle 12, the volume V2 is smaller than the volume V1.

In the present embodiment, in each nozzle 12, the volume (second volume) V2 of the extending portion (second extending portion) 22 excluding the flow passage 17 is smaller than the volume (first volume) V1 of the extending portion (first extending portion) 21 excluding the flow passage 17. Furthermore, in each nozzle 12, the dimension L2 of the extending portion 22 in the projection direction is smaller than the dimension L1 of the extending portion 21 in the projection direction. For this reason, in each nozzle 12, the projection length of the extending portion 22 where the projecting end E2 (ejection port 18) is provided is small. Reduction in the length of projection of the extending portion 22 from the extending portion 21 in each nozzle 12 prevents excessive increase of electrical field intensity in the space of the vicinity of the projecting end E2 (ejection port 18) of each nozzle 12, even when a voltage is applied between the nozzles 12 and the collection body 5, etc. It is thereby possible to effectively prevent the adhesion of the fiber (material liquid) 100 to the projecting end. E2 of each nozzle 12 and its vicinity in a state where the liquid material is ejected from each ejection port 18.

In the present embodiment, the thickness of the extending portion 22 is smaller than the thickness of the extending portion 21. For this reason, a configuration wherein the volume V2 of the part of the extending portion 22 excluding the flow passage 17 is smaller than the volume V1 the part of the extending portion 21 excluding the flow passage 17 is easily achieved by making the dimension L2 of the extending portion 22 along the projection direction smaller than the dimension L1 of the extending portion 21 along the projection direction.

In the present embodiment, in each nozzle 12, the flow passage 17 extends inside the extending portions 21 and 22, and extends from the connecting portion (the root of the projecting portion) E1 connecting to the head main body 11 to the projecting end E2. For this reason, in each nozzle 12, the extension length of the flow passage 17 is the same or approximately the same as a sum (L1+L2) of the dimensions L1 and L2, and this length is considered to be large. Since the extension length of the flow passage 17 is large in each nozzle 12, the frequency of contact between a material liquid flowing in the flow passage 17 and the inner peripheral surface (peripheral surface of the flow passage 17) becomes higher in each nozzle 12. Since the frequency of contact between the material liquid and the inner peripheral surface in each nozzle 12 becomes higher, electric charge easily moves from each nozzle 12 to the material liquid in a state where a voltage is applied between the nozzles 12 and the collection body 5, etc. It is thereby possible to ensure in each flow passage 17 a high charge density of a material liquid immediately before the ejection from the ejection port 18. Higher charge intensity of a material liquid immediately before the ejection from the ejection port 18 in each flow passage 17 allows appropriate ejection of the material liquid from the ejection port 18 against the collection body 5 and the substrate, etc.

In the present embodiment, in each nozzle 12, the cross-sectional area (diameter) of the flow passage 17 becomes uniform from the connecting portion (position of connection) E1 connecting to the head main body 11 to the projecting end E2. For this reason, in the flow passage 17 of each nozzle 12, the area of the cross section perpendicular to the extension axis P is smaller not only in the projecting end E2 and its vicinity but also in the connecting portion E1, connecting to the head main body 11, and its vicinity. For this reason, the frequency of contact between the material liquid and the inner peripheral surface of each nozzle 12 becomes higher even in the connecting portion E1, connecting to the head main body 11, and its vicinity. It becomes easier for the electric charge to move from each nozzle 12 to the material liquid, and it is thereby possible to ensure in each flow passage 17 a higher charge density of the material liquid immediately before the ejection from the ejection port 18.

(Modifications)

In the first modification shown in FIG. 4, in each nozzle 12, the outer diameter of the extending portion 21 is not uniform in the area between the connecting portion E1 connecting to the head main body 11 and the connecting portion E3 connecting to the extending portion 22. In the present modification, the outer diameter decreases in the extending portion (first extending portion) 21 of each nozzle 12, toward the connecting portion E3 connecting to the extending portion 22. Accordingly, the extending portion 21 of each nozzle 12 is formed in a tapered shape in which the outer diameter becomes smaller as the area in the extending portion 21 becomes closer to the projecting end E2. In the present modification, however, in each nozzle 12, the outer diameter of the extending portion 22 is uniform (constant or substantially constant) from the connecting portion E3 connected to the extending portion 21 to the projecting end E2. Furthermore, in each nozzle 12, the outer diameter of the extending portion (second extending portion) 22 is smaller than the outer diameter of the extending portion 21 excluding the connecting portion E3. In the present modification, in each nozzle 12, the outer diameter at the connecting portion E3 between the extending portion 21 and the extending portion is the same or substantially the same as the outer diameter at the projecting end E2. Furthermore, unlike the foregoing embodiment, etc., in each nozzle 12, a step in a radial direction is not formed in the connecting portion E3 between the extending portions 21 and 22.

In the present modification, in each nozzle 12, the area of the cross section of the flow passage 17 perpendicular to the direction in which the flow passage 17 extends is uniform (constant or substantially constant) from the connecting portion E1 to the head main body 11 to the projecting end E2. For this reason, in the present modification, in the extending portion (second extending portion) 22 of each nozzle 12, the thickness from the flow passage 17 to the outer peripheral surface is uniform (constant or substantially constant) in the area between the connecting portion E3 connecting to the extending portion 21 (the root of the extending portion 22) to the projecting end E2. In other words, if the thickness of the projecting end E2 from the flow passage 17 to the outer peripheral surface is defined as “thickness T2”, the thickness in any site between the connecting portion E3 and the projecting end E2 from the flow passage 17 to the outer peripheral surface is the same or substantially the same as the thickness T2 in the extending portion 22 of each nozzle 12.

In the present modification, the thickness from the flow passage 17 to the outer peripheral surface decreases in the extending portion (first extending portion) 21 of each nozzle 12, toward the connecting portion E3 connecting to the extending portion 22. Accordingly, the thickness of the extending portion 21 of each nozzle 12 decreases as the area in the extending portion 21 becomes closer to the projecting end E2. Furthermore, in each nozzle 12, the thickness of the extending portion (second extending portion) 22 is smaller than the thickness of the extending portion (first extending portion) 21 excluding the connecting portion E3. In the present modification, in each nozzle 12, the thickness at the connecting portion E3 between the extending portion 21 and the extending portion 22 is the same or substantially the same as the thickness at the projecting end E2.

With the above-described configuration, in the present modification, the area of the cross section perpendicular to the extension axis P excluding the flow passage 17 in the extending portion 22 is smaller than the area of the cross section perpendicular to the extension axis P excluding the flow passage 17 in the extending portion 21. In the present modification, in each nozzle 12, the dimension L2 of the extending portion 22 in the direction along the extension axis P is smaller than the dimension L1 of the extending portion 21 in the direction along the extension axis P. For this reason, in each nozzle 12, the volume (second volume) V2 of the extending portion (second extension) 22 excluding the flow passage 17 is smaller than the volume (first volume) V1 of the extending portion (first extension) 21 excluding the flow passage 17. Accordingly, the operations and advantageous effects similar to those of the foregoing embodiment, etc. are achieved in the present modification.

In the second modification shown in FIG. 5, similarly to the modification shown in FIG. 4, the outer diameter decreases in the extending portion (first extending portion) 21 of each nozzle 12, toward the connecting portion E3 connecting to the extending portion 22. In each nozzle 12, the outer diameter of the extending portion 22 becomes uniform (constant or substantially constant) from the connecting portion E3 connected to the extending portion 21 to the projecting end E2. Furthermore, in each nozzle 12, the outer diameter of the extending portion (second extending portion) 22 is smaller than the outer diameter of the extending portion (first extending portion) 21 excluding the connecting portion E3.

In the present modification, however, in each nozzle 12, the area of the cross section of the flow passage 17 perpendicular to the extension direction of the flow passage 17 is not uniform in the area between the connecting portion E1 connecting to the head main body 11 and the connecting portion E3 between the extending portions 21 and 22. Furthermore, in the present modification, the flow passage 17 of each nozzle 12 has a sectional area changing portion 25 formed in the area between the connecting portion E1 connecting to the head main body 11 and the connecting portion E3, and sectional area uniform portion 26 formed in the area between the connecting portion E3 connecting the extending portion 21 to the extending portion 22 and the projecting end E2 (ejection port 18). In the sectional area changing portion 25, the closer the area becomes to the connecting portion E3, in other words, to the projecting end E2, the more the area of the cross section of the flow passage 17 perpendicular to the extension direction of the flow passage 17 decreases. In the sectional area uniform portion 26, the area of the cross section of the flow passage 17 perpendicular to the extension direction of the flow passage 17 is uniform (constant or substantially constant) in the area from the connecting portion E3 to the projecting end E2.

In the present modification, in the extending portion (second extension) 22 of each nozzle 12, the thickness from the flow passage 17 to the outer peripheral surface becomes uniform (constant or substantially constant) from the connecting portion E3 connecting to the extending portion 21 (the root of the extending portion 22) to the projecting end E2. In other words, if the thickness of the projecting end E2 from the flow passage 17 to the outer peripheral surface is defined as “thickness T2”, the thickness in any site between the connecting portion E3 and the projecting end E2 from the flow passage 17 to the outer peripheral surface is the same or substantially the same as the thickness T2 in the extending portion 22 of each nozzle 12.

In the present modification, in each nozzle 12, the dimension L2 of the extending portion 22 in the direction along the extension axis P is smaller than the dimension L1 of the extending portion 21 in the direction along the extension axis P. Furthermore, in each nozzle 12, the volume (second volume) V2 of the extending portion (second extending portion) 22 excluding the flow passage 17 is smaller than the volume (first volume) V1 of the extending portion (first extending portion) 21 excluding the flow passage 17. Accordingly, the operations and advantageous effects similar to those of the foregoing embodiment, etc. are achieved in the present modification.

As described above, the number of nozzles 12 provided in the electrospinning head 2 suffices as long as it is at least one. In the foregoing embodiment, etc., a single nozzle row 13 is constituted by the plurality of nozzles 12; however, a plurality of nozzle rows similar to the nozzle row 13 may be formed in the electrospinning head 2.

In the third modification shown in FIG. 6, as the nozzles 12, the nozzles 12A and 12B are provided on the outer peripheral surface of the head main body 11. In the present modification, a plurality of nozzles 12A and a plurality of nozzles 12B are provided. In the present modification, a plurality of nozzles (first nozzles) 12A are arranged at the same or substantially the same angle positions with respect to each other in a direction around the longitudinal axis C, and a plurality of nozzles (second nozzles) 12B are arranged at the same or substantially the same angle positions with respect to each other in the direction around the longitudinal axis C. For this reason, in the present modification, the plurality of nozzles 12A are arranged along the longitudinal axis C, and constitute the nozzle row (first nozzle row) 13A. The plurality of nozzles 12B are arranged along the longitudinal axis C, and constitute the nozzle row (second nozzle row) 133.

The nozzles 12B are arranged in a manner such that they are deviated from the nozzles 12A in the direction around the longitudinal axis. For this reason, the nozzle row 133 is formed in a manner such that it is deviated from the nozzle row 13A in the direction around the longitudinal axis. In the present modification, both the nozzles 12A and 12B are arranged on the side where the collection body 5 is located with respect to the longitudinal axis C. For example, the nozzles 12A are arranged deviated for about 60 degrees from the nozzles 12B around the longitudinal axis C.

On the outer peripheral surface of the head main body 11, the nozzles 12A and 12B are arranged in a zigzag relationship. Furthermore, the nozzles 12A and 12B are alternately arranged in the direction along the longitudinal axis C. For this reason, one of the nozzles (second nozzles) 12B is arranged between two adjacent nozzles (first nozzles) 12A according to the direction along the longitudinal axis C.

In the present modification, a nozzle 12B is arranged between adjacent nozzles 12A in the direction along the longitudinal axis C. For this reason, in the collection body 5 or the substrate, the fiber 100 is accumulated by the nozzles 12B also in the area between the adjacent nozzles 12A in the direction along the longitudinal axis C. It is thereby possible to effectively prevent local accumulation of the fiber 100 on the collection body 5 or the substrate.

In the present modification, the extending portions 21 and 22 are formed in each of the nozzles 12A and 12B similarly to the nozzles 12 in the foregoing embodiment, etc. Furthermore, in each of the nozzles 12 and 12B, the flow passages 17 and the ejection ports 18 are formed in a manner similar to the formation of any of the nozzles 12 in the foregoing embodiment, etc. Accordingly, the operations and advantageous effects similar to those of the foregoing embodiment, etc. are achieved in the present modification.

According to at least one of the foregoing embodiment or modifications, a second extending portion projects from a first extending portion in a projection direction in each nozzle of an electrospinning head, and the second extending portion constitutes the projecting end of the nozzle. Furthermore, a second volume of the second extending portion excluding the flow passage is smaller than a first volume of the first extending portion excluding the flow passage, and a dimension of the second extending portion along the projection direction is smaller than that of the first extending portion. It is thereby possible to provide an electrospinning head and an electrospinning apparatus capable of ejecting a material liquid appropriately from an ejection port toward a collection body and a substrate.

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions. 

What is claimed is:
 1. An electrospinning head comprising: a head main body in which a storage hollow capable of storing a material liquid is formed in the inside; and a nozzle made of an electrically conductive material and projecting from an outer peripheral surface of the head main body, a flow passage which communicates with the storage hollow being formed inside the nozzle, and an ejection port of the flow passage being formed at a projecting end of the nozzle from the head main body, wherein the nozzle comprises: a first extending portion that constitutes a connecting portion to the outer peripheral surface of the head main body, a part of the first extending portion excluding the flow passage having a first volume; and a second extending portion that further projects from the first extending portion toward a projection direction of the nozzle and constitutes the projecting end of the nozzle, a part of the second extending portion excluding the flow passage having a second volume smaller than the first volume, and a dimension of the second extending portion along the projection direction being smaller than that of the first extending portion.
 2. The electrospinning head according to claim 1, wherein an area of a cross section of the flow passage perpendicular to an extension direction of the flow passage is uniform from the connecting portion of the nozzle connecting to the outer peripheral surface of the head main body to the projecting end of the nozzle.
 3. The electrospinning head according to claim 1, wherein a thickness of the second extending portion from the flow passage to the outer peripheral surface of the nozzle is smaller than that of the first extending portion.
 4. The electrospinning head according to claim 3, wherein the thickness of the second extending portion from the flow passage to the outer peripheral surface of the nozzle is uniform up to the projecting end of the nozzle.
 5. The electrospinning head according to claim 4, wherein the thickness of the first extending portion from the flow passage to the outer peripheral surface of the nozzle is uniform up to a connecting portion connecting to the second extending portion.
 6. The electrospinning head according to claim 4, wherein the thickness of the first extending portion from the flow passage to the outer peripheral surface of the nozzle decreases as an area in the first extending portion becomes closer to the connecting portion connecting to the second extending portion.
 7. A spinning apparatus comprising: the spinning apparatus according to claim 1, an electric power source that applies a voltage to the nozzle of the electrospinning head. 